Defrosting apparatus for refrigerator components and method



y 1961 .T. A. SCHILLING ,0 DEFROSTING APPARATUS FOR REFRIGERATOR COMPONENTS AND METHOD 2 Sheets-Sheet 1 Filed Jan. 12. 1959 INVENTOR: THOMAS A. 5cm: NG-

BY at, 41 W ATTORNEY-'5 May 30, 1961 Filed Jan. 12. 1959 T. A. SCHILLING DEFROSTING APPARATUS FOR REFRIGERATOR COMPONENTS AND METHOD 2 Sheets-Sheet 2 AIR.

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Arron sYs United States Patent 9 DEFROSTING APPARATUS FOR REFRIGERATQR COMPONENTS AND METHOD Thomas A. Schilling, 8303 Thoreau Drive, Bethesda, Md.

Filed Jan. 12, 1959, Ser. No. 786,148

4 Claims. (Cl. 62-80) This invention relates to apparatus for defrosting deep freeze devices such as hollow deep freeze plates, commonly known as hold-over plates, and the like carried by a truck body or located in a deep freeze room or in any location Where ice forms on refrigerated surfaces.

It is customary in the delivery of ice cream, for example, to use truck bodies, whose interiors are refrigerated by hollow plates each containing a solidified eutectic solution. Such solution is normally liquid, but is frozen so as to create a very low temperature within the enclosure. In withdrawing packages from the truck, outside atmosphere enters and causes the entrance of moisture which, in turn, forms a coating of ice on the freezing plates. The solidification or freezing of the eutectic solution is performed in the home plant and the melting of the solution in the plates of a truck is substantial during a days run of the truck. Thus, at night, the plates have to be refrigerated again. When this process has been repeated a few times, the moisture which has collected on the plates during the daytime in the delivery process results in the building up of such a layer of ice on the plates that they are insulated to where they will no longer absorb heat and, thus, fail to maintain cold the ice cream in the truck.

When the coating of ice on the plates becomes so heavy or thick as to render the device inoperable for the purpose of refrigerating the contents of the truck during a days trip, the only way they had heretofore of eliminating this coating of ice was to open up the truck and allow it to stand a day or longer until the ice had melted therefrom.

In the case of a deep freeze room which has holdover plates disposed about the same, there is no wayof getting rid of this ice except to scrape it off the plates or to transfer all the contents of the deep freeze room to another deep freeze room and open the then empty room and cut out the refrigeration and allow the ice to melt. 1

In order to simplify the defrosting of refrigerated or cold surfaces, such as hold-over plates, it is an object of this invention to provide a pliable air-tight bag, which can be placed around the deep, freeze plateswith an open end of the bag then sealed to make it air tight. Then by the introduction of air pressure into the bag, the ice will be cracked and dislodged from the bag. After the ice has been removed, by enlarging the bag around each deep freeze plate by the introduction of air pressure, the operator may then introduce an anti-freeze solutioninto the bag between the freezer plate and the bag. Any suitable anti-freeze solution may be used, such as glycerin, ethylene glycol or the like. :In order to cause the bags to stick closely to the deep freeze plates and to prevent the bags. from becoming insulators, the bags are each equipped with a valve fitting to which a suction source may be connected to evacuate the air and cause the bag to fit snugly against the plate, whereby a coating of antifreeze solution is provided between the bag and the deep freeze plate to prevent the bag'frcm freezing to the plate Patented May 30, 1961 and to also insure thermal conductivity between the plate and the bag.

Some of the objects of the invention having been stated, other objects will appear as the description proceeds when taken in connection with the accompanying drawings in which- Figure l is an isometric view of a truck having its refrigerated compartment or body equipped with a preferred embodiment of the invention;

Figure 2 is an isometric view of one of the pliable enclosures or defrosting bags removed from its freezer plate;

Figure 3 is a transverse cross-sectional view taken along line 3-3 in Figure 2;

Figure 4 is a cross-sectional view taken substantially along line 44 in Figure 1, showing a coating of ice on the improved plate-enclosing bag and also showing means attached to the roof of the truck body for supporting the plates;

Figure 5 is a view similar to Figure 4 omitting the supporting means therefor and showing the bag expanded with the ice thus broken;

Figure 6 is an enlarged detailed view of the rectangular broken-line portion indicated at 6 in Figure 4 and showing ice or frost adhering to the bag on the frozen plate; and

Figure 7 is a schematic view showing the apparatus and how it is used, whether it be on a truck or in a deep freeze room or the like.

Since the present invention is particularly useful for defrosting holdover freezer plates of the type used in the enclosure or body of a commercial ice-cream delivery truck, the present invention is disclosed in association with such a truck. However, it is distinctly understood that the present invention is also applicable for use in defrosting freezer plates of other types, including those used in deep freeze rooms of cold storage plants, for example.

Referring more specifically to the drawings, said commercial ice-cream delivery truck is shown in Figure 1 and includes a body or enclosure 10 having an access door d in its rear wall. As is usual, all the walls of the body 10 may be of hollow insulated construction. The upper wall of body 10 is broken away in Figure 1 for purposes of clarity. However, a portion of said upper wall is shown in Figure 5, wherein it is indicated at 11. a

The interiors of the bodies of refrigerated trucks are normally maintained cold; at sub-freezing temperatures, by means of so-called hold-over plates which may be arranged in any convenient manner in the truck body. In this instance, truck body 10 is provided with three closely spaced, hollow, hold-over or vacuum freezing plates 12,

13, 14 which are removably suspended from top wall :11 of truck body 10. A typical suspension means is shown in Figure 4 wherein it will be observed that each corner portion of each freezer plate rests upon the horizontal lower portion of a substantially Z-shaped bracket 15, suitably secured to the upper wall '11, as by screws 16, and the freezer plates are clamped upon the lower horizontal portions of brackets 15 by clamp brackets 17 penetrated by bolts 20.

The lower wall of each freezer plate 12, 13, 14 supports a tubular freezing coil C, opposedends of which protrude through a corresponding side wall of each freezer plate so as to be coupled to a suitable charging or refrigerating apparatus, such as that shown schematically in the right-hand portion of Figure 7. Hold-over truck plates, such as plates 12, 13, 14 may be used with .any commercial refrigerant and can be charged by anin- I In this instance, the freezing plates 12, 13, 14 are arranged in series, to the extent that corresponding ends of the freezing coils therein are interconnected by branch pipe lines 22. The ends of the coils in the distal portions of the rearmost and foremost freezing plates 12, 14 are detachably connected to respective conduits or pipe lines 23, 24. Suitable fittings or couplings may be provided on protruding opposite ends of each coil C (Figure 7) for detachably connecting the same to the respective pipe lines 22, 23, 24.

During the manufacture of commercial freezer plates, after the freezing coils have been installed therein, the plates are filled with a eutectic solution which is frequently termed as a hold-over solution, such solution being commercially available in formulae corresponding to the temperature range desired. Eutectic solutions have a relatively low freezing point and, depending upon the individual characteristics of the solutions and the temperature range desired, eutectic solutions solidify at temperatures ranging from minus 20 Fahrenheit to plus 26 Fahrenheit. The eutectic solution may or may not be under vacuum within the sealed freezing plate. In either event, a freezing plate will absorb considerable heat for a considerable length of time before melting or becoming liquified. Only when the eutectic solution has absorbed considerabl heat and started to become liquified is it necessary to recharge the same by passing a refrigerant through the coil C in the corresponding freezing plate.

It will be noted that corresponding ends of pipe lines 23, 24, remote from respective freezing plates 12, 14 protrude through one wall of truck body 10 and have suitable quick connect-disconnect couplings 26 thereon for detachably connecting the same to pipe lines 30, 31 of the refrigerating apparatus (Figure 7). The refrigerating apparatus may be of usual construction and includes a compressor 32, a heat exchanger 33 and a condenser 34. Pipe line 31 also has an expansion valve 35 interposed therein and both pipe lines 30, 31 have suitable shut-off valves 36 therein which may be closed when pipe lines 23, 24 are disconnected from pipe lines 30, 31. In some instances, the refrigerating apparatus may be carried on the truck. The structure and operation of refrigerating machines are Well known and a further description thereof if thus deemed unnecessary.

In some installations, particularly in deep freeze rooms, hold-over plates are not equipped with coils such as coil C, although such freezing plates contain a hold-over or eutectic solution. Plates of the latter type are merely placed in a refrigerating room having a refrigerating machine connected thereto for solidifying the eutectic or hold-over solution therein, whereupon the freezing plates are removed from the freezing room and installed in the cold storage room or other location, as the case may be.

As heretofore stated, hold-over plates or freezing plates of the character described are located in enclosures containing perishable food stuffs or other items which must be maintained under refrigeration, and it is frequently necessary to open such enclosures, with the result that outside atmosphere enters the enclosures and causes moisture to collect on the freezing plates, which moisture is subsequently frozen and forms a coating of frost or ice on the freezing plates. As the ice builds up on the freezing plates, it has an insulating effect and gradually reduces the efficiency of the freezing plates so the ice has to be removed from time to time.

The defrosting of plates 12, 13 and 14 associated with ice-cream trucks is particularly difficult and time consuming and requires that the truck be placed out of operation sometimes for more than a day. In order to reduce considerably the time required to defrost freezing plates of the character described, I have provided a pliable enclosure, preferably in the form of a thin plastic bag broadly designated at 40, for enclosing therein each of the freezing plates 12, 13, 14. Eachbag may be made from any pliable material capable of being tightly sealed 4 against leakage of air and which will cling to the respective freezing plate when air is exhausted from the bag. Clear polyethylene or similar thermoplastic material serves well for this purpose, because it is susceptible to heatsealing, is light-weight, pliable, easily handled and stored, and is relatively inexpensive to procure. The bags 40 may also be made from rubber, neoprene or the like.

Each plastic bag may be made from a single piece of material. However, in its preferred embodiment, the bag is best shown in Figure 2 as comprising a pair of substantially rectangular sheets of plastic or other pliable or resilient material, indicated at 41, 42 which are interconnected along their opposed side edges 43 and one corresponding pair of end edges 45, as by heat-sealing. A pair of spaced tubular members 46, 47 is positioned between the corresponding end edge portions 45 of sheets 41, 42 before heat-sealing the same, so these tubular members 46, 47 communicate with the interior of bag 40. Before bag 40 is installed on a corresponding freezing plate, one end of the bag remains open along edges 50, to facilitate positioning the bag over the corresponding freezing plate. The outer ends of tubular members 46, 47 are preferably provided with quick connect-disconnect couplings 52, 53 to facilitate passing air and liquid into and out of each bag 40, as will be later described.

Each bag 40 should be somewhat larger than the freezing plate it is to enclose. In order to install each bag 40, freezing plates 12, 13, 14 should be removed from brackets 15 (Figure 4) and then the bag 40 should be drawn over the respective freezing plates so as to completely enclose the same. Thereafter, the edges 50 (Figure 2) at the open end of each bag are sealed together, either by heat-sealing the same together or adhesively connecting the same together or by any other suitable means, or the edges 50 of the bags may be adhesively or otherwise sealed, in engagement with the freezing plates. Each bag is first drawn over that end of each respective freezer plate opposite from the end to which conduits or pipelines 23 and/or 22 and 24 are connected so that, when the open end of the bag is closed in the manner heretofore described, the edge portions 50 of sheets 41, 42 of the respective bag 40 are also tightly sealed around the protruding ends of the corresponding coil C. Thereafter. the plates 12, 13, 14 may be positioned on brackets 15 and clamped in place by clamp brackets 17.

Pipe lines 22, 23, 24 may then be connected to the corresponding coils C Within the respective freezing plates 12, 13 and 14 in the manner heretofore described for circulating a refrigerant through the coils to freeze and solidify the eutectic solution within each of the freezing plates 12, 13, 14.

In order to defrost each freezing plate 12, 13, 14, it is necessary that air pressure is introduced into each bag 40 to expand the bag. On the other hand, each bag should tightly engage the outer surfaces of the corresponding freezing plate so as to permit subsequent enlargement of the bag by air pressure and to also prevent the bags from insulating said outer surfaces of the freezing plates and to provide a hard surface on which the frost may collect. Accordingly, in order to prevent bags 40 from becoming frozen in engagement with the surfaces of the respective freezing plates, and to insure thermal conductivity therebetween, a relatively small amount of a suitable anti-freeze solution A (Figure 6), such as glycerine, ethylene glycol or the like, is injected into each bag 40, after it has been positioned about a respective freezing plate, through either of the tubular members 46 and 47. The anti-freeze solution is preferably pumped into each bag 40 under pressure so as to provide a thin film of said solution between all surfaces of each freezing plate 12, 13, 14 and the inner surfaces of the bag 40.

After the anti-freeze solution A has been introduced into each bag 40, the air is evacuated from each bag to produce a vacuum or negative pressure therein which causes each bag 40 to snugly engage substantially all surfaces of the respective freezing plates. This spreads or squeezes the anti-freeze into a thin layer as shown in Figure 6. It will be noted that this also causes the antifreeze solution to flow into all hollow or irregular surfaces on the freezing plates and forms a bond between each bag and its respective freezing plate.

In order that the anti-freeze solution may be introduced into each bag 40 and to facilitate the introduction of or evacuation of air into and out of each bag 40, I have provided a pair of pipe lines or conduits 54, 55 in the body of the truck. All the tubular members 46 are detachably connected to pipe line 54 by means of couplings 52 and all the tubular members 47 are detachably connected to pipe line 55 by means of couplings 53.

The ends of pipe lines 54, 55 remote from bags 40 on freezing plates 12, 13, 14 protrude through one wall of enclosure 10 and have respective manually operable valves 56, 57 connected thereto exteriorly of the enclosure 10. Valves 56, 57 may also have respective quick connect-disconnect couplings 60, 61 thereon for connecting the same to respective conduits 62, 63 leading from a source of compressed air and a source of vacuum or negative pressure respectively designated at 64, 65. The source of compressed air may be replaced by or include a source of anti-freeze solution in instances where it is desired to replenish the supply of anti-freeze solution between plates 12, 13, 14 and the respective bags 40.

It is thus seen that I have provided a novel apparatus and method for defrosting freezing plates in which each plate is enclosed by a sealed pliable container or bag which is caused to tightly engage the corresponding freezing plates by producing negative pressure therein and by the use of an anti-freeze solution between each plate and its corresponding bag. When frost or ice forms on the bags surrounding the freezing plates, it is merely necessary to introduce compressed air into each bag to fracture the ice so that it will fall free of the bag.

It is apparent that this defrosting procedure can be performed while the doors of the truck of Figure 1, for example, are closed and while the interior of the truck is still at a very low temperature, due to the fact that an anti-freeze solution is provided between each bag and the corresponding freezing plates. Thereafter, an operator may enter the truck and any frost or ice that remains deposited upon the bags, but has been previously dislodged therefrom, can be brushed off the bags on the plates with a broom or other suitable means. The supply of anti-freeze solution within the bag 40 need not be replenished each time the bags are expanded by the compressed air.

In order to defrost the plates covered with bags 40, it is merely necessary to drive the truck into an area closely adjacent a source of compressed air and to couple a compressed air line, such as pipe 62, to the pipe line 55 while valve 56 remains closed. The flow of compressed air into the bag will expand the same and thus break the ice and frost so that it will fall therefrom or so it can be brushed off the same. Thereafter, the valve 57 may be closed and valve 56 opened to evacuate air from the bags 40 and cause the same to snugly engage all the surfaces of the corresponding freezing plates. Thereafter, the valve 56 may be closed so as to maintain negative pressure within the bags 40-.

In the drawings and specification, there has been set forth a preferred embodiment of the invention and although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being defined in the claims.

I claim:

1. A method of conditioning and defrosting freezing plates having a solidified eutectic therein which includes enclosing each freezing plate in a sealed pliable bag having a film of anti-freeze solution between the bag and the exterior surfaces of the plate, then creating a negative pressure Within each bag to cause the same to snugly engage the exterior surfaces of the respective freezing plate, whereby ice may subsequently collect on the freezing plate during the course of refrigeration effected by said freezing plate, then admitting compressed air into each bag to enlarge the same whereby the ice collected on the outer surface of the bag is cracked and dislodged therefrom, and repeating the steps as prescribed.

2. A method of conditioning and defrosting freezing plates which includes enclosing each freezing plate in a sealed pliable bag, introducing an anti-freeze solution into the bag to form a film between the bag and the exterior surfaces of the plate, then creating a negative pressure within each bag to cause the same to snugly engage the exterior surfaces of the respective freezing plates, whereby ice may subsequently collect on the outer surface of the bag on the freezing plate during the course of refrigeration effected by said freezing plate, then admitting compressed air into each bag to expand the same, the anti-freeze solution facilitating the separation of the inner surfaces of the bag from the exterior surfaces of the freezing plate, and whereby the ice which may have collected on the outer surface of the bag is cracked and dislodged therefrom, and then repeating the steps as prescribed.

3. The combination with a hollow freezer plate having an eutectic solution therein of a pliable relatively thin walled bag enclosing said freezer plate and being sealed against leakage of air therethrough, a film of anti-freeze solution between the inner surfaces of said bag and the exterior surfaces of said freezer plate, means for creating negative pressure within said bag so the bag tightly engages the outer surfaces of said freezer plate, and means for introducing compressed air into said bag for expanding the same to thereby break and dislodge any ice or frost which may have collected thereon in the interim between the creation of negative pressure in the bag and the introduction of compressed air thereinto.

4. The combination with a freezer plate of a pliable relatively thin walled plastic bag enclosing said freezer plate and being sealed against leakage of air therethrough, a film of anti-freeze solution between the inner surfaces of said bag and the exterior surfaces of said freezer plate, means for evacuating air from within said bag so the bag tightly engages the outer surfaces of said freezer plate, and means for introducing fluid pressure into said bag for expanding the same to thereby break and dislodged any ice or frost which may have collected thereon in the interim between the creation of negative pressure in the bag and the introduction of fluid pressure thereinto.

References Cited in the file of this patent UNITED STATES PATENTS 2,139,244 Nauert Dec. 6, 1938 2,516,586 Peltier July 25, 1950 2,554,050 Neubeck May 22, 1951 2,616,271 Knowles Nov. 4, 1952 2,683,359 Green July 13, 1954 2,749,020 Baxter June 5, 1956 2,790,591 Rosen Apr. 30, 1957 

